The present invention relates in general to automotive suspension systems, and, more specifically, to determining ride height for a pair of wheels that are coupled by an anti-roll system.
Automotive suspension systems may include one or more sensors for detecting the relative position of one or more portions of the suspension with respect to the fixed frame (e.g., chassis or unibody) of the vehicle. A relative displacement obtained from the sensors provides a “ride height” that may be used by several different types of adaptive systems.
In Continuously Controlled Damping (CCD) systems, for example, a ride height position sensor is used on each wheel to determine its instantaneous position and rate of movement. Variable dampers are controlled to improve ride characteristics in response to the sensor signals.
In the case of vehicles using load leveling or air suspension systems, it is necessary to know the ride height of the vehicle in order to determine whether correction of the ride height is required. When the ride height is lower than a prescribed “trim” limit, an adjustable suspension unit may be given a command to increase ride height. Conversely, in the event that the ride height exceeds the prescribed “trim” limit, the adjustable suspension unit may be given a command to lower, or decrease, the ride height.
Adaptive headlamp systems employ adjustable headlamps that can be aimed to maintain a desired angle with respect to the road ahead even when the vehicle tilts or rocks. Thus, ride height differences between the left and right sides or the front and back of the vehicle are measured in order to determine a correction to the aiming of the headlamps that keeps the light beams pointed as desired.
Most vehicles utilize independent suspensions for each of the wheels. Therefore, ride height has typically been determined using mechanical sensors that directly measure the height of every wheel. Potentiometers, optical encoders, and other displacement sensors are used. The sensors and associated hardware such as fasteners and brackets can be difficult to fit into available spaces. Since a typical vehicle requires ride height sensors at all four wheels, the costs for the parts, assembly, and servicing for the sensors can be significant. It would be desirable to reduce the costs and packaging space requirements for ride height sensing.